android.view.ViewConfiguration

源碼地址:http://grepcode.com/file/repository.grepcode.com/java/ext/com.google.android/android/4.2_r1/android/view/ViewConfiguration.java?av=f

 

/** 
* 包含了方法和標準的常量用來設置UI的超時、大小和距離 
*/ 
public class ViewConfiguration { 
    // 設定水平滾動條的寬度和垂直滾動條的高度，單位是像素px 
    private static final int SCROLL_BAR_SIZE = 10; 

    //定義滾動條逐漸消失的時間，單位是毫秒 
    private static final int SCROLL_BAR_FADE_DURATION = 250; 

    // 默認的滾動條多少秒之後消失，單位是毫秒 
    private static final int SCROLL_BAR_DEFAULT_DELAY = 300; 

    // 定義邊緣地方褪色的長度 
    private static final int FADING_EDGE_LENGTH = 12; 

    //定義子控件按下狀態的持續事件 
    private static final int PRESSED_STATE_DURATION = 125; 
    
    //定義一個按下狀態轉變成長按狀態的轉變時間 
    private static final int LONG_PRESS_TIMEOUT = 500; 
    
    //定義用戶在按住適當按鈕，彈出全局的對話框的持續時間 
    private static final int GLOBAL_ACTIONS_KEY_TIMEOUT = 500; 
    
    //定義一個touch事件中是點擊事件還是一個滑動事件所需的時間，如果用戶在這個時間之內滑動，那麼就認爲是一個點擊事件 
    private static final int TAP_TIMEOUT = 115; 
    
    /** 
     * Defines the duration in milliseconds we will wait to see if a touch event 
     * is a jump tap. If the user does not complete the jump tap within this interval, it is 
     * considered to be a tap. 
     */ 
    //定義一個touch事件時候是一個點擊事件。如果用戶在這個時間內沒有完成這個點擊，那麼就認爲是一個點擊事件 
    private static final int JUMP_TAP_TIMEOUT = 500; 

    //定義雙擊事件的間隔時間 
    private static final int DOUBLE_TAP_TIMEOUT = 300; 
    
    //定義一個縮放控制反饋到用戶界面的時間 
    private static final int ZOOM_CONTROLS_TIMEOUT = 3000; 

    /** 
     * Inset in pixels to look for touchable content when the user touches the edge of the screen 
     */ 
    private static final int EDGE_SLOP = 12; 
    
    /** 
     * Distance a touch can wander before we think the user is scrolling in pixels 
     */ 
    private static final int TOUCH_SLOP = 16; 
    
    /** 
     * Distance a touch can wander before we think the user is attempting a paged scroll 
     * (in dips) 
     */ 
    private static final int PAGING_TOUCH_SLOP = TOUCH_SLOP * 2; 
    
    /** 
     * Distance between the first touch and second touch to still be considered a double tap 
     */ 
    private static final int DOUBLE_TAP_SLOP = 100; 
    
    /** 
     * Distance a touch needs to be outside of a window's bounds for it to 
     * count as outside for purposes of dismissing the window. 
     */ 
    private static final int WINDOW_TOUCH_SLOP = 16; 

   //用來初始化fling的最小速度，單位是每秒多少像素 
    private static final int MINIMUM_FLING_VELOCITY = 50; 
    
    //用來初始化fling的最大速度，單位是每秒多少像素 
    private static final int MAXIMUM_FLING_VELOCITY = 4000; 

    //視圖繪圖緩存的最大尺寸，以字節表示。在ARGB888格式下，這個尺寸應至少等於屏幕的大小 
    @Deprecated 
    private static final int MAXIMUM_DRAWING_CACHE_SIZE = 320 * 480 * 4; // HVGA screen, ARGB8888 

    //flings和scrolls摩擦力度大小的係數 
    private static float SCROLL_FRICTION = 0.015f; 

    /** 
     * Max distance to over scroll for edge effects 
     */ 
    private static final int OVERSCROLL_DISTANCE = 0; 

    /** 
     * Max distance to over fling for edge effects 
     */ 
    private static final int OVERFLING_DISTANCE = 4; 

}